The use of ultrafiltration for removing interferences in the Lowry microassay of extractable proteins in natural rubber latex gloves
2001
Esah Y. | Mok, K. L. | Lai, P. F.
This study evaluates the use of ultrafiltration in removing micro-solutes that might interfere in the Lowry microassay. Reference proteins, glove extracts and 1, 3-diphenylguanidine were subjected to ultrafiltration using a commercial concentrator, which has a membrane filter of 3 kD molecular weight cutoff. Separated fractions were analysed for their reactivity by the MS 1392: 1998 Lowry mircoassay. Purified reference proteins with molecular weights greater than 3 kD, showed high retentate recovery, which verified the efficacy of separation of the ultrafiltration unit. Micro-solutes were evidently present in both the non-interfering and interfering glove extracts. Irrespective of their original extractable protein (EP) values, the micro-solute content for the non-interfering glove extracts was relatively constant at 28%. This is in contrast with the marked variation observed for the interfering glove extracts. The ultrafiltration process caused an irrecoverable loss of approximately 5% - 6%. The total recovery was comparable for both the non-interfering and interfering glove samples. This indicates that the micro-solutes and/or their interfering components were not detrimental to the filter membrane, causing no+ obvious degradation of membrane integrity. Some samples may however, necessitate higher number of wash cycles to completely remove the interference and obtain accurate EP values.
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